1. Field Of The Invention
The present application falls in the general field of those training devices that are adapted to propel forcibly, into the air, spherical objects such as tennis balls or the like for practice or training purposes. In a more particular sense the invention relates to a means for imparting oscillatory motion bodily to an entire device of the character described, about an axis that, if not completely vertical, at least has a vertical component. The invention is directed to a programming-type improvement in ball-propulsion equipment already known, in respect to the means for creating oscillating motion of the discharge barrel of the equipment, thus to time the oscillation and the extent of angular travel thereof and in addition pre-select a ball-drop pattern in a given extent of such angular travel, relative to the successive discharge of the tennis balls during normal rotation of a distribution or feed magazine.
2. Description Of The Prior Art
Tennis ball propulsion devices, for use as training aids, are already very well known in and of themselves. A typical propulsion device of the type stated may be seen in U.S. Pat. No. 4,027,646 issued June 7, 1977. In such devices, there is a hopper, a rotary feed magazine or distributor having angularly spaced ball receiving openings or sleeves, and a conduit that extends from the distributor location to the discharge outlet of the device. Passage of a ball from the distributor through the conduit occurs within a pressurizing chamber, in such fashion that the balls are successively fed through the conduit. Pressure is built up behind each ball until it reaches a value such as to cause the ball to be forcibly discharged.
In the prior art, various means have heretofore been devised for changing or varying the path in which the successively propelled objects will be directed. It is known, for example, to cause the discharge barrel of such a device to be oscillated, that is, moved in a continuous back-and-forth or side-to-side motion, so that the user will be required to run back-and-forth across the tennis court, to return each ball, thereby to obtain practice in executing forehand as well as backhand strokes, increase his or her stamina, and otherwise obtain added benefits from the use of the propulsion device. See for example, Sweeton et al U.S. Pat. No. 4,006,726 issued to the assignee of the present application, and the patents cited therein.
The prior art devices have been effective in respect to achieving the broad objects of varying the paths along which the tennis balls or other spherical objects are discharged. However, the prior art has had certain disadvantages, including, for example, the provision of oscillatory motion only through the medium of expensive electrical, electronic, or complex mechanical devices.
Further, in the prior art such devices have in many instances been required to be built into the complete device, in such fashion that the user would be prevented from manufacturing, with the same components, both standard and programmed oscillating type discharge mechanisms.
In still other prior art devices, it has not been possible for a user to adjust, with maximum speed and ease, the width of the oscillating path in which the discharge end of the barrel is to travel. And in yet other cases the user is prevented from disengaging the oscillating mechanism except with considerable difficulty.
Thus, the prior art has broadly suggested the concept of timing oscillation of a discharge barrel in relation to the feeding of balls into the propulsion device, but heretofore, so far as is known, the prior art has not suggested a mechanical linkage between the ball feeding and the discharge mechanisms, such as to optionally connect or disconnect the oscillation-producing means, adjust swiftly and easily the extent of oscillating travel in relation to the quantum and frequency of ball delivery, and, in general, facilitate the manufacture of propulsion devices of this type so as to incorporate an oscillating mechanism that is inexpensive, simple, and trouble free, and that can be either incorporated in or left out of the propulsion device, according to the desires of the manufacturer and without changing in either instance the design or assembly of the basic propulsion device.
In the above-mentioned U.S. Pat. No. 4,233,953, the deficiencies of the prior art devices have been overcome by a programmable oscillating mechanism incorporated in a propulsion device of the character described. That device operates with full efficiency. The invention of U.S. Pat. No. 4,233,953, however, is directed to imparting oscillatory motion to the barrel assembly per se, while the rest of the structure remains stationary. While this is entirely suitable and feasible for incorporation in propulsion devices in which the barrel assembly is located at the top and to the rear portion of the equipment (as in U.S. Pat. No. 4,233,953), the mechanism of U.S. Pat. No. 4,233,953 is not adapted for use on propulsion devices of the kind shown in U.S. Pat. No. 4,027,646. In those devices the barrel is mounted at the front end of and near the bottom of the support structure or housing of the propulsion equipment.